Methods of rolling

ABSTRACT

A method of rolling small sections is provided in which the metal to be rolled is passed through a plurality of successive roll stands having grooved rolls, while tension is applied to the metal in successive stands and is varied between the stands depending upon the relative filling of the grooved rolls in each stand whereby variations in conditions of wear in the roll grooves from one stand to another are offset by the changes in tension between stands. The variations in tension may be provided by varying the roll rotation speed.

United States Patent [1 1 Bindernagel 1 Sept. 4, 1973 [54] METHODS OF ROLLING 3,540,248 11/1970 Hostetter et a1. 72/8 3 3 4 197 B d l 72 4 [75] Inventor: Ali Bindernagel, 5 H/ I m emage eta! I22 Dusseldorf-Gerreshein, Germany Primary Examiner-Milton S. Mehr [73] Assignee. Friedrich Kocks, w

Dusseldorflaeneshein Germany Attorney-Eugene F. Buell, Walter F. Buell et a1.

[22] Filed: July 14, 1971 [21] App]. No.: 162,627 [57] ABSTRACT A method of rolling small sections is provided in which [30] Fol-mg Apphcatlon Pnomy Data the metal to be rolled is passed through a plurality of July 1970 Germany P 20 35 successive roll stands having grooved rolls, while tension is applied to the metal in successive stands and is [52] US. Cl 72/205, 72/235, 72/366 varied between the Stands depending upon the relative [51] Int. Cl B21b 39/08, B2lb 1/18 filling f the grooved ll i h tand whereby varia- [58] Fleld of Search 72/234, 235, 224, tions in conditions of wear in the to" grooves from one 72/205 stand to another are offset by the changes in tension between stands. The variations in tension may be pro- [561 References cued vided by varying the roll rotation speed.

UNITED STATES PATENTS 3,243,983 4/1966 Norlundh et al 72/235 6 Claims, N0 Drawings METHODS OF ROLLING This invention relates to methods of rolling and particularly to a method of rolling light sections, chiefly wire, under tension in a multi-stand rolling mill, e.g. one having non-adjustable rollers, the finished cross section of the work-material or strands being adjustable within limits.

Nowadays, when rolling wire, rolling mills are used which comprise a plurality of stands arranged one after the other and combined to form a block, the rolling operation being effected under tension between all the stands. The tension ensuring trouble-free rolling is affected by several factors, particularly the roller grooving, the cross section of the first pass for the workmaterial, and the rotational speed of the rollers. While the roller grooving constitutes a predetermined, constant factor (when considering a short period of time), the cross section of the first pass and the tension may be varied, the tension being a function of the cross section of the first pass. When the rotational speed of the rollers is constant, an increase in the cross section of the first pass results in a reduction in the tension between all the stands in the block, while a reduction in the cross section of the first pass effects an increase in tension.

The range of variation of the cross section of the first pass is dependent upon the roughing stands connected in front of the block. The upper limit of the tension is particularly dependent upon the tensile strength of the work-material and upon the rollers which, in the case of great tension, are subjected to considerable wear. Theoretically, the lower limit can be fixed at zero, which would correspond to tension-free rolling, although, for reason of safety, the lower limit is fixed somewhat higher in dependence upon the rolling conditions in order still to obtain a perceptible tension between the stands under all operating conditions.

However, over a long period of operation, the roller grooving determined by the configuration of the freshly fitted rollers is not constant and varies by virtue of the unavoidable wear of the rollers, the amount of wear increasing towards the delivery end of the block owing to the greater rotational speed of the rollers or the greater throughput length of the work-material. When the cross section of the first pass is constant, this variation in the grooving, occasioned by wear, results in an increase in the tension throughout the entire block, so that there is an increase in the reduction of the cross section occasioned by tension.

The optimum extent to which the sizing passes are filled, particularly the finishing sizing pass, necessarily falls below the optimum extent by virtue of the increase in the diameter of the sizing passes conditioned by wear and by virtue of the associated increase in the reduction of the cross section occasioned by tension, so that a non-circular cross section of the wire is produced, which is disadvantageous during further reduction of the wire by drawing for example. Thus, a circular cross section of the wire is always desired and can be obtained only by maintaining a specific optimum extent to which the finishing sizing pass is filled.

Thus, to maintain the optimum extent to which the sizing passes are filled when the sizing passes are widened by wear, particularly the finishing sizing pass, the cross section of the first pass is increased to effect a corresponding increase in the final cross section. However, this possibility of adjustment is limited, since the optimum extent to which the sizing passes can be filled cannot be attained by increasing the cross section of the first pass after a specific amount of wear has occurred, although the wire, which would be obtained with optimum filling of the sizing passes widened by wear, would still be within the admissible range of to]- erance. In order to continue rolling circular wire, the sets of rollers, particularly at the finishing sizing passes, frequently have to be removed before the actual limit of wear has been reached and have to be replaced by fresh or reconditioned rollers.

A feature of the invention is to provide a method of rolling light sections, chiefly wire, in which an optimum extent to which the sizing passes are filled, particularly the finishing sizing pass, can be maintained even when the sizing passes have been subjected to a considerable amount of wear.

In accordance with the invention, the under-filling of the sizing passes caused by variation in the roller grooving conditioned by wear, particularly the under-filling of the final sizing passes subjected to greatest wear, is at least partially compensated for by reducing the tension between the stands.

The extent to which the sizing passes are filled can be controlled by reducing the tensioneven when the possibilities of control by increasing the cross section of the first pass have not yet been fully utilized. The amount of wear on the rollers with respect to time, which increases with increasing tension, can be reduced by keeping the tension to a minimum from the outset.

Consequently, by using the method of the present invention, one set of rollers can beused to roll circular wire for a longer period of time than hitherto, the range of tolerance of the cross section of the wire being fully utilized on the one hand and, on the other hand, the absolute service life of the rollers can be increased.

The method according to the invention is further particularly described hereinafter with reference to a preferred embodiment.

A block comprising a plurality of stands is used as the rolling mill, one group of stands or, if required, all the stands, being driven by two motors. One motor in the form of a group drive then drives the stands over a primary range of speed, while the second motor superimposes on each stand an additional and variable range of speed by way of a differential drive.

Only the superimposed additional speed is varied to control the finished cross section emerging from the rolling block, and adds a speed increment to the primary speed in one direction of rotation and subtracts a speed decrement in the other direction of rotation.

At the commencement of the rolling operation, the block operates at an average tension with an average cross section of the first pass for example. The variation in the roller grooving which is occasioned by wear, and by which the sizing passes at the delivery end are widened more rapidly than the sizing passes at the input end, results in an increase in tension throughout the entire block without a variation in the cross section of the first pass. At the same time there is a continuously increasing under-filling of the sizing passes at the delivery end, particularly of the finishing sizing pass which is chiefly responsible for the roundness of the wire.

The rolling mill has to be adjusted before the operating state is reached in which the rolling mill produces non-circular, unserviceable wire or in which the tension would exceed the upper admissible limit.

initially, the difference in the rolling conditions may readily be compensated for by varying the cross section of the first pass, since, by appropriately increasing the cross section of the first pass, the tension is reduced on the one hand and, on the other hand, the final cross section or the filling of the finishing sizing pass is increased. When an operating state is reached in which the sizing passes have been worn beyond a predetermined amount, the extent to which the sizing passes are filled can be varied only slightly even by large variations in the cross section of the first pass, until it is finally impossible to increase the extent to which the sizing passes are filled by further increasing the cross sections of the first pass.

However, the sizing passes are normally not worn to an extent where wire could not be produced by optimum adjustment of the extent to which the sizing passes are filled and which is within the range of tolerance. The tension which has increased owing to the variation in the sizing passes is now reduced by appropriate adjustment of the motor supplying the additional speed, so that the reduction in cross section occasioned by tension is reduced, thus increasing the final cross section without varying the cross section of the first pass, i.e., the extent to which the finishing sizing pass is filled is increased and, of course, that of the preceding sizing passes.

The tension, necessarily increasing by virtue of the variation in the roller grooving occasioned by wear, can be reduced from the outset by appropriate regulation of the additional motor without varying the cross section of the first pass. Advantageously, however, both variable factors will be used to adjust the finished cross section.

It will be appreciated that adjustment of the tension may also be used in the opposite case when the finishing sizing pass is over-filled, this being effected by increasing the tension by supplying a corresponding addi tional speed. This increases the reduction in cross section occasioned by tension, so that the final cross section decreases together with the extent to which the finishing sizing pass is filled.

The extent to which the sizing passes are filled, or the cross-sectional area of the finished product, are adjustable over a substantially greater range than hitherto by virtue of combining variation in the entry crosssectional area'and variation in the tension. Furthermore, the variation in tension effected by regulating the additional motor is very flexible, so that it is possible very rapidly to compensate for flaws in the finished product caused by not maintaining the optimum extent to which the sizing passes are filled.

In the foregoing specification, certain preferred emobidments and practices of this invention have been set out, however, it will be obvious that this invention may be otherwise practiced within the scope of the following claims.

I claim:

I. A method of rolling small sections under tension in a multi-stand rolling mill comprising the steps of a. passing the metal to be rolled through a plurality of successive roll stands having grooved rolls,

b. applying tension to the metal in the successive roll stands, and

c. varying the tension on the metal in said stands depending upon the relative filling of the grooved sizing rolls in each stand whereby variations in the conditions of wear in the roll grooving from one stand to another is offset by changing the tension between the stands.

2. A method as claimed in claim 1 wherein the tension is reduced in proportion to the amount of increase in wear of the grooving of the rolls.

3. A method as claimed in claim 1 in which the tension is reduced by effecting variations in the speeds at which the rollers are driven.

4. A method as claimed in claim 3 in which the speed variation is achieved by an adjustable additional drive motor acting on a differential drive between a main drive motor and the relevant stands.

5. A method as claimed in claim 1 in which the rollers are non-adjustable.

6. A method as claimed in claim 1 in which the variations in wear conditions are also partially offset by adjusting the rollers defining the first pass.

EUNITED STATES PATENT oi i icE QERTEFECATE QF (IQRRECTION Pat n 3,756,060 Dated September 4, 1973 Inventor(s) Ali Bindernagel It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Under the heading UNITED STATES PATENTS, "Norlundh et a1. should read -Norlindh et al.-.

The attorney of record should read "Eugene F. Buell et a1.", delete -Walter F. Buell--.

Column 4, line- 12, "emobidments" should read -embodiments-.

Signed and sealed this 25th day of December 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents USCOMM-DC 60376-P6D 1 us GOVERNMENT PRINTING OFFICE: I959 0-366-334, 

1. A method of rolling small sections under tension in a multistand rolling mill comprising the steps of a. passing the metal to be rolled through a plurality of successive roll stands having grooved rolls, b. applying tension to the metal in the successive roll stands, and c. varying the tension on the metal in said stands depending upon the relative filling of the grooved sizing rolls in each stand whereby variations in the conditions of wear in the roll grooving from one stand to another is offset by changing the tension between the stands.
 2. A method as claimed in claim 1 wherein the tension is reduced in proportion to the amount of increase in wear of the grooving of the rolls.
 3. A method as claimed in claim 1 in which the tension is reduced by effecting variations in the speeds at which the rollers are driven.
 4. A method as claimed in claim 3 in which the speed variation is achieved by aN adjustable additional drive motor acting on a differential drive between a main drive motor and the relevant stands.
 5. A method as claimed in claim 1 in which the rollers are non-adjustable.
 6. A method as claimed in claim 1 in which the variations in wear conditions are also partially offset by adjusting the rollers defining the first pass. 